1. Field of the Invention
The present invention relates to a developer supply of an image forming apparatus, and more particularly, to a developer supplying apparatus with a separate developer cartridge, and to a developing apparatus having the same.
2. Description of the Related Art
FIG. 1 illustrates a conventional image forming apparatus. As illustrated, the conventional image forming apparatus comprises a feeding unit 10 to load printing media, an image forming unit 20 to form an image on the printing media supplied from the feeding unit 10, a fixing unit 30 to fix the image on the surface of the printing medium by applying heat and pressure to the developer image formed on the printing medium, and a delivery unit 40 to discharge printing medium to exterior.
The image forming unit 20 may include a photoconductor, a charging unit to charge the photoconductor to an electric potential, a light exposure unit to form an electrostatic latent image on the photoconductor, a developing apparatus to develop the electrostatic latent image on the photoconductor by applying the developer thereto, and a transfer unit to transfer the image developed on the photoconductor onto the printing medium.
The developing apparatus includes a developing roller to apply the developer on the photoconductor, and a developer supplying roller to supply the developer to the developing roller. A developing apparatus may be classified into one of an integrated type in which the developer is held within the casing as the developing apparatus, and a separate developer cartridge type, in which the developer is held in a separated casing (hereinafter referred to as a developer cartridge), which may be detachable from the developing cartridge, which houses the other portions, e.g., the developing roller, the developer supplying roller, or the like, of the developing apparatus.
In the case of a removable developer cartridge type, the developer may be supplied from the developer cartridge to the developing cartridge by mainly either the use of an auger that transports the developer or by allowing the developer to free fall.
When an auger is used, the auger is typically disposed in the path connecting the developer cartridge with the developing cartridge, and the developer is supplied by the rotation of the auger. According to this method, a horizontal or a level path connecting the developer cartridge with the developing cartridge is provided. If the path is sufficiently slanted, the developer can still free fall or slide along the slope independent of the rotation of the auger so that a precise control of the amount of the developer being supplied may be difficult. In some cases, the straight path may not be possible because other components may be in the way, and thus a meandering path may be necessary, which requires a flexible auger to be used, which in turn increases the material cost.
In the method of using the free fall of the developer, the path connecting the developer cartridge with the developing cartridge is vertical or is slanted with a sufficient slope to allow the developer to free fall into the developing cartridge. According to this method, however, lumps of the developer may form along the path. Because the viscosity and/or the fluidity of the developer may vary according to the surrounding environmental conditions and/or the state of the particular developer, over time the developer particles may aggregate together to form lumps, and may accumulate, e.g., along the walls of the path. As a result, the motor for supplying the developer may not operate properly, and an overload of the same may occur, and/or the developer may not be supplied properly so that the quality of the printed image may suffer.